Machine element or mechanism – Elements – Gear casings
Reexamination Certificate
1999-10-08
2001-04-17
Marmor, Charles A (Department: 3681)
Machine element or mechanism
Elements
Gear casings
C476S010000
Reexamination Certificate
active
06216559
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an installation structure of a pressure control valve that functions to prevent hydraulic surge under low temperature by maintaining a discharge pressure of an oil pump at a predetermined value, and more particularly to an installation structure of a relief valve for a toroidal type continuously variable transmission (CVT) applied to a rear-wheel drive vehicle.
Conventional automatic transmissions for rear-wheel drive vehicles have been generally arranged to dispose a transmission control valve assembly under a transmission mechanism. Further, a relief valve for maintaining an oil discharge pressure of an oil pump is generally disposed at a lower surface of a transmission case so as to be directed toward an oil pan. In view of preferably preventing hydraulic surge under low temperature, it is preferable to employ a large size relief valve.
SUMMARY OF THE INVENTION
However, if such a large size relief valve is disposed at the lower surface of the transmission case so as to be perpendicular to a bottom surface of the oil pan, it is necessary to increase a depth of the oil pan to receive the large size relief valve therein. This results in enlarging a diametrical dimension of the transmission. Further, if the relief valve is installed at the lower surface of the transmission case to which the control valve assembly is installed, a distance between the oil discharge port and the relief valve increases. This results in degrading the performance of the relief valve.
It is an object of the present invention to provide an improved installation structure of a pressure control valve. The present invention preferably prevents the generation of oil surging under low temperature while ensuring an-excellent relief valve performance of the pressure control valve. Further, these advantages of the present invention are ensured without increasing a diametrical dimension of a transmission case to which the pressure control valve is installed.
A valve installation structure according to the present invention comprises a torque converter housing of a torque converter. A transmission case of a transmission is integrally connected to the torque converter housing. The transmission case has an oil supply port for a control valve assembly of the transmission and a projecting portion extending toward the torque converter housing. An oil pump cover of an oil pump integrally installed between the torque converter housing and the transmission case. The oil pump cover has an oil discharge port from which oil is supplied to the oil supply port of the control valve assembly. The projecting portion of the transmission case is located in the vicinity of the oil discharge port. A hydraulic passage connects the oil discharge port and the oil supply port. A pressure control valve is connected to the hydraulic passage. The pressure control valve is disposed in the projecting portion of the transmission case.
REFERENCES:
patent: 4297918 (1981-11-01), Perry
patent: 5230258 (1993-07-01), Nakano
patent: 5254056 (1993-10-01), Nakano
patent: 5540631 (1996-07-01), Lohr, III et al.
patent: 5676026 (1997-10-01), Tsuboi et al.
patent: 6110070 (2000-08-01), Nagai et al.
Nakano Masaki
Tanoue Kimito
Foley & Lardner
Marmor Charles A
Nissan Motor Co,. Ltd.
Parekh Ankur
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